Indeed, relating the causal character of marginally trapped tubes to explicit physical/geometrical quantities in the spacetimes is of huge interest to both mathematical and numerical relativists. A relatively recent appproach to dealing with spacetimes admitting a unit tangent directing and some preferred spatial directiion normal to the tangent one, seems a good candidate for such project. This so-called \(1+1+2\)  formalism [1]}, [2]}, [3]}, [4]} characterizes a spacetime in a covariant manner just as the \(1+3\)  formalism, but with new scalar, vector and tensor quantities defined on the 2-space. The first use of this formalism to analyze black hole horizons was by Ellis et al. [5]}, where considerations were given to an astrophysical collapse scenario. In [6]} and [7]}, Sherif and coauthors extended the results in [5]} to more general spacetimes, both using an original approach, as well as adapting an approach by Booth et al. (see [9]}, [10]} and references therein), to the \(1+1+2\)  covariant variables. A series of established results were obtained in a relatively easy manner, as well as a couple of original results like a classifications scheme of marginally trapped tubes up to diffeomorphisms and causal characters. For specific examples, the authors considered spacetimes in the class of locally rotationally symmetric spacetimes with no rotation and no spatial twist.
